title: Risk behaviors for HIV in sexual partnerships of San Francisco injection drug users.
abstract: While injection drug users (IDU) in the USA are known to form sexual partnerships with IDU as well as non-IDU, scientific research is lacking regarding risk behaviors for HIV transmission within these partnerships. Such information could aid HIV-prevention efforts among IDU and could also explain the relatively low prevalence of HIV among non-IDU heterosexuals in US cities such as San Francisco. Using data from a cross-sectional sample of San Francisco IDU we estimated (1) the prevalence of IDU-IDU and IDU-non-IDU sexual partnerships, (2) the frequency of serodiscordant unprotected intercourse in IDU-IDU and IDU-non-IDU sexual partnerships, and (3) the frequency of concurrence of sexual risk and injection-related risk within IDU-IDU sexual partnerships. An estimated 68% of sexually active San Francisco IDU is in IDU-IDU partnerships. Our analysis suggests that compared to IDU-non-IDU partnerships, IDU-IDU partnerships include a greater rate of episodes of serodiscordant unprotected intercourse (incidence rate ratio: 10.2; 95% confidence interval: 2.1-50.7). In fact, our data suggest that 92% of serodiscordant sexual episodes involving IDU are attributable to IDU-IDU pairings. Unprotected intercourse and needle sharing occur concurrently in an estimated 29% of IDU-IDU partnerships. Our data suggest that HIV-transmission risk is higher within IDU-IDU partnerships than it is within IDU-non-IDU partnerships. This disparity could explain the relatively low prevalence of HIV among non-IDU heterosexuals in San Francisco. We recommend that HIV-prevention efforts among IDU continue to address sexual risk behaviors for HIV transmission in addition to injection-related risk behaviors, with emphasis on IDU-IDU partnerships.
authors.affiliation: a Center for Public Health Research , San Francisco Department of Public Health , San Francisco , CA , USA.
authors.forename: Yea-Hung
authors.initials: YH
authors.lastname: Chen
authors.forename: Willi
authors.initials: W
authors.lastname: McFarland
authors.forename: Henry Fisher
authors.initials: HF
authors.lastname: Raymond
mesh_terms: D000293:Adolescent; D000328:Adult; D017280:Condoms / Q000706:statistics & numerical data*; D003430:Cross-Sectional Studies; D055030:Drug Users / Q000523:psychology; D005260:Female; D015658:HIV Infections / Q000517:prevention & control* / Q000635:transmission; D007722:Health Knowledge, Attitudes, Practice; D006703:Ill-Housed Persons; D006801:Humans; D008297:Male; D016485:Needle Sharing / Q000523:psychology / Q000706:statistics & numerical data*; D015995:Prevalence; D012307:Risk Factors; D012309:Risk-Taking; D012495:San Francisco / Q000453:epidemiology; D012747:Sexual Partners; D015819:Substance Abuse, Intravenous; D011795:Surveys and Questionnaires